Generally, in a measurement system, an illumination unit forms and radiates grid pattern light to a measurement object, and an imaging unit receives light reflected from the measurement object and measures the shape of the measurement object using the received light.
That is, in order for the measurement system to measure the shape of the measurement object, the light reflected from the measurement object has to be received by the imaging unit. When the light is irregularly reflected from the surface of the measurement object, the irregularly reflected light spreads in all directions. Thus, the imaging unit may receive the reflected light irrespective of the position thereof.
However, when the measurement object has a mirror reflection surface, such as a mirror or a glass surface, on the surface thereof, the light may be regularly reflected from or may pass through the surface. When the light is regularly reflected, it is difficult to sense the light by an imaging unit at a fixed position since the regularly reflected light travels only in a predetermined direction. In addition, when the light passes through the measurement object, the amount of light incident on the imaging unit is reduced, and it is difficult to sense the light by the imaging unit at a fixed position. Accordingly, it is difficult to perform an accurate measurement of the measurement object.